The present invention relates to a gas turbine engine and more particularly to a vane and blade outer air seal (BOAS).
Gas turbine engines generally include fan, compressor, combustor and turbine sections positioned along an axial centerline often referred to as the engine axis of rotation. The fan, compressor, and turbine sections each include a series of stator and rotor blade assemblies. An array of blades and an axially adjacent array of vanes are referred to as a stage.
Each stator assembly, which does not rotate (but may have variable pitch vanes), increase the efficiency of the engine by guiding core gas flow into or out of the rotor assemblies. Each rotor blade assembly includes a multiple of blades extending outwardly from the circumference of a disk. Platforms extend laterally outward from each blade and collectively form an inner radial flowpath boundary for core gas passing through the rotor assembly.
An outer case, including a multiple of blade outer air seals (BOAS), provides an outer radial flow path boundary. A multiple of BOAS are typically provided to accommodate thermal and dynamic variation typical in a high pressure turbine (HPT) section of the gas turbine engine. The BOAS are subjected to relatively high temperatures and receive a secondary cooling airflow for temperature control. The secondary cooling airflow is communicated into the BOAS then through annular cooling channels within the BOAS. The annular cooling channels have been reduced in size and increased in numbers so as to increase the secondary cooling airflow efficiency.
Disadvantageously, these relatively small internal passageways may become plugged with particulate in the secondary cooling airflow. Conventional HPT BOAS particulate plugging mitigation is either nonexistent or is manifested as particulate entrapment features in the secondary flow system upstream of the BOAS. Either technique may be less than effective with these relatively small internal passageways.